Download Flash and Video is a great download helper tool that lets you download Flash games and Flash videos (YouTube, Facebook, Dailymotion, Google Videos and more) with a single click.The downloader is very easy to use.

YouTube High Definition is a powerful tool that will let you automatically play all YouTube videos in HD (High Definition), turn off annotations, change video player size, auto stop videos, auto mute videos, control embedded videos and much more.

Instant lyrics on YouTube, Spotify, Deezer, 8tracks, SoundCloud and many other music sites in a flexible panel. 40+ sources ensure that lyrics are always found. Simple to use and highly customizable. (formerly called "YouTube Lyrics by Rob W")

Image Block X allows you to disable loading images in Firefox, allowing you to save data when you're on a capped connection, and browse faster when you're on a slow connection. It is a spiritual successor to Image Block, rewritten as a web extension.